Hey, folks. Latest project is an SCA-35 that I bought that is "gonna take a lot of love," as the song says. I have read so many good things about this little amp and have found Dave Gillespie's work on it so interesting, that I am going for a total restore using all three of Dave's boards (the pre-amp, power supply upgrade with his Enhanced Fixed Bias circuit, and both output amplifier boards with Dave's 7199-to-6GH8/6U8 conversion). Having done work on Fisher and Scott receivers and amplifiers, I decided it was time to look at Dynaco and these units are very, very well documented here on AK and in various other places on the web, including various vendors with all sorts of parts and mods in addition to Dave's very good offerings.
Below are a few "before shots"--this one looks like it was stored in a barn for 15 or 20 years. The chassis and bottom plate are heavily rusted around the transformers, things are very dirty with corrosion in several places and the workmanship on the assembly is suspect, particularly the soldering. The output circuit boards have seen a lot of heat and all the switches and controls need thorough cleaning or replacement. The plug was cut off the power cord and the fuse and holder cap were missing. The back of the chassis was bent.
The front panel and the knobs are not bad, but there are some dings in the upper edge that will have to be addressed.
The tube complement was quite good. RCA 12AX7's and 7199's all tested quite strong for mutual conductance. For 6BQ5's, two RCA that look like GE's (with the dots), one Dynaco label, and one GE label. All but the Dynaco tested good and fairly well matched at tube checker conditions, but we'll see how they look under power.
Obviously, I didn't even try to power this one up and instead decided to do pretty much a complete tear down and restore. We'll see how that goes in the next few weeks.
Below are a few "before shots"--this one looks like it was stored in a barn for 15 or 20 years. The chassis and bottom plate are heavily rusted around the transformers, things are very dirty with corrosion in several places and the workmanship on the assembly is suspect, particularly the soldering. The output circuit boards have seen a lot of heat and all the switches and controls need thorough cleaning or replacement. The plug was cut off the power cord and the fuse and holder cap were missing. The back of the chassis was bent.
The front panel and the knobs are not bad, but there are some dings in the upper edge that will have to be addressed.
The tube complement was quite good. RCA 12AX7's and 7199's all tested quite strong for mutual conductance. For 6BQ5's, two RCA that look like GE's (with the dots), one Dynaco label, and one GE label. All but the Dynaco tested good and fairly well matched at tube checker conditions, but we'll see how they look under power.
Obviously, I didn't even try to power this one up and instead decided to do pretty much a complete tear down and restore. We'll see how that goes in the next few weeks.